what is mysql optimizer

mysql optimizer refers to the query optimizer. The SQL statement will use the query optimizer to optimize the query before querying. The syntax is such as "select uid,name from user where gender = 1;".

Optimizer: Query optimizer

The SQL statement will use the query optimizer to optimize the query before querying. He uses the "select-projection-join" strategy for querying.

You can understand it with an example: select uid,name from user where gender = 1;

This select query first selects based on the where statement, instead of querying all the tables first. Perform gender filtering;

This select query first performs attribute projection based on uid and name, instead of taking out all attributes and then filtering;

Connect these two query conditions to generate the final query result.

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